This had been one big summer of Sunday disappointments playing in the final group.

It started with the 82 he shot in the final round of the U.S. Open at Pebble Beach. Then came the shock of Whistling Straits, when Johnson didn't realize he was in one of a thousand bunkers on the 18th hole and was given a two-shot penalty for touching the sand with his club, knocking him out of the playoff at the PGA Championship.

Even in the FedEx Cup, he was in the last group at The Barclays three weeks ago only to shoot 72 and tie for ninth.

This one turned out differently.

Tied for the lead with two holes to play, knowing the 405-yard 17th hole that bends to the right with bunkers protecting the left side, Johnson reached for his driver and blasted his biggest shot of the final round at Cog Hill.

"I knew I needed to hit a good tee ball because it was going to be my best chance of making a birdie," Johnson said. "I was just trying to cut a drive, hold it against the wind and get it around the corner a little bit. And I hit it perfect."

It set up a sand wedge from 94 yards that Johnson hit to 2 feet for the go-ahead birdie. He followed with another clutch drive and a 40-foot par down the ridge that settled tap-in range from the hole for a par and a 2-under 69. He wound up with a one-shot victory over Paul Casey, moving Johnson to No. 2 in the FedEx Cup standings.

For all the heartache he endured in his breakout season, Johnson showed he is as resilient as he is powerful.

"To finally get it done, especially after all the things I've gone through this summer ... it can't feel any better," Johnson said.

Johnson's biggest rival had been playing in the last group on Sunday.

Another rivalry was renewed Sunday when Tiger Woods and Phil Mickelson played together for the first time this year. There was far more at stake for Woods than Mickelson, for the world's No. 1 player needed to finish around fifth to get into the Tour Championship.

He wasn't even close.

Mickelson put five strokes between them over seven holes and matched the best round of the day at 4-under 67. Woods didn't get under par for the first time all week until a birdie on the 17th hole. He finished with a 70 to tie for 15th, not nearly enough to crack the top 30 in the FedEx Cup standings and get to East Lake.

It will be the first time in his pro career that Woods has not been invited to a tournament.

"I didn't play well in the beginning of the year and I didn't play well in the middle of the year," Woods said. "Now I'm starting to play well. I'm headed in the right direction."

Mickelson didn't get all he wanted out of these playoffs. He started at No. 4 and slid to No. 10 after his tie for eighth at Cog Hill, his first top 10 since the U.S. Open at Pebble Beach.

Beating Woods is a small consolation, although their head-to-head record playing in the same group now stands at 11-11-4.

"He certainly brings out the best in me, and I enjoy being paired with him," Mickelson said.

For Johnson, the best is still around the corner.

In one year, the 26-year-old American has established himself as one of golf's rising stars. He won the Pebble Beach National Pro-Am in February to become the first player since Woods in 1998 to go straight from college to PGA Tour titles in each of his first three years.

No other American in his 20s has more than his four career victories.

And where some see failure, Johnson sees only opportunity. True, he could easily have captured two majors this year. Johnson takes pleasure in knowing that he played in the final group five times this year, a sign of consistency.

Casey, meanwhile, had a chance to make a statement of his own.

He was No. 9 in the world when European captain Colin Montgomerie declined to pick him for the Ryder Cup. It was shocking to leave Casey off the team, leading to innuendoes and hard feelings.

Casey had a three-shot lead on the back nine until making three straight bogeys, then failed to give himself a birdie look inside 25 feet over the last three holes. He closed with a 69.

"It was myself against the golf course, 72 holes, and I played it one shot worse than Dustin Johnson," Casey said.

With the 70-man field at Cog Hill narrowed to the final 30, the BMW Championship offered plenty of drama away from the leaders.

Charlie Wi appeared set for his first Tour Championship until making bogeys on the last two holes, missing a 12-foot par putt on the final hole. That moved Bill Haas up to No. 30. Then came Matt Kuchar, who needed a birdie for any hope of getting into a playoff at Cog Hill. He ran his putt 3½ feet by the hole, then missed it coming back. Kuchar was in a two-way tie for third, and the bogey moved him into a three-way tie for fourth. That allowed K.J. Choi to crack the top 30.

Ryan Moore, the 54-hole leader, was alone in third place when he sent his second shot over the 18th green. He smartly played away from the pin to avoid chipping into the water and took his bogey, which kept him in the top 30. If Moore had made double bogey, he would have fallen out of the Tour Championship.

Johnson earned a small measure of redemption. He likely moves to No. 12 in the world with his fourth career victory.

"I know I've had some failures — I don't know if I'd call them failures — I've had a few mishaps," Johnson said. "To come back and get it done, I'm very proud of myself. I think I've handled everything very well, and now I've got to look forward to two weeks from now."